Theoretical study is neglected in immunology. Other disciplines have appreciated that theoretical studies have a very high payoff in three main areas. First, an experiment that tests a theory is optimally cost- effective because its outcome affects all of the other data that went into making that theory. Second, the theory provides much more accurate long range predictability than any of the data and their derived models that went into making it, because a theory reveals hidden universalities by permitting the ability to isolate aberrant observations. Third, the theory permits control and manipulation of nature in a rational way, and this is the investigators' unique goal. Four theories are being developed that together cover most of the immune behavior: the Associative Recognition Theory of the Self-Nonself discrimination, the B-Protecton Theory of humoral responsiveness, the T- Protecton theory of cell-mediated responsiveness and the Adapton Theory of the determination of the class of the response. These theories must be connected together to provide a comprehensive conceptual framework and, to this end, a prototype computer program has been written based on cellular automata principles to provide a Synthetic Immune System (i.e., SIS). The Associative Recognition, B-Protecton, and Adapton Theories have been incorporated into SIS in outline form although aspects of each have been developed in considerable detail (e.g., the Dual Recognitive-Single Receptor Model of the T-cell Receptor as part of T-Protecton Theory). A working SIS program is in place to deal with these theories, but its main utility will be realized when it is written in a more general form that will permit computer experimentation by revealing inconsistencies in data and concept. It will be possible to determine which assumptions are consistent with a functioning immune system and which are not. Thus far, a startling new view of humoral immune responsiveness has been revealed with practical consequences related to vaccination and treatment with antibodies. Lastly, it has become clear that practical manipulation of the immune system will more likely derive from an understanding of how the class of the response is accomplished ban from considerations involving the Self-Nonself discrimination.